Hey guys, i have a 90 4runner v6 5spd, the other day it started to have a fluctuating idle problem. It seems when i'm out of gear and the rpms have dropped towards normal idle, it starts to fluctuate btwn 900-1400rpms then stabilizes at 1300ish rpms and stays this way until next time i take the truck out of gear and/or in gear with the clutch pressed in. since i did search and couldn't really find anything concrete, pressing the brakes doesn't change anything, it doesn't start after i had pressed the brakes, like others have experienced. Also I haven't noticed any overheating (being that i own two cars with HG problem, i always have a eye on that), I have an occasional hesitation i should have done a tune up before winter, but never got around to it. also the oil is ok, its due for a change but i checked it it was normal. I was leaning towards the IAC or EGR. you guys think it might possible be the timing? Idk maybe its because i'm sick and on a bunch of meds but i can't seem to think of what exactly might be the problem. THanx for the help guys!

 

First thing to look for is vacuum leaks. But since you haven't changed anything this is unlikely. Under the category of 'things that go bad' the TPS seems to be at the top of the list.

 

hmm, i'll have to check the tps with the vantage on monday.

also i want to add that after further driving it around it, it does looks like the brakes effect it doing it. also i think i'm going to do a smoke test too on monday (force smoke thru the vacuum system to see for leaks)

anything else you guys can think of let me know. thanx!

 

wheres does it idle at

 

when it fluctuates it goes from 850ish to 1400ish, then smooths out to about 1250ish. but i think normally its at about 1100ish, when it does do the fluctuating thing. Eitherway i think its idling a little to high, i think before it used to be lower.

 

the idle is to high try adjsuting it if that dont solve the problem must be a vacuum leak

 

yea, i found the screw earlier when i checked the oil yet again. I'm going to add that to the list of things to check on monday. I don't have anything to give me a digital rpm read out here at home. I want to set it back to spec, i also want to check and adjust the valve clearences. I don't think thats been done in a long time.

How often do you guys find that the valves need adjusting??

 

Check the air intake hose that goes into the actual intake manifold. It's about 3inches in diameter, the pcv hose is attached to it. They are made of a harder rubber and like to tear at the bends, this will casue your rpms to vary under aceleration or decelration, and at idle as it lets intake air exscape. Mine was having idle problem and surging problem, when I indstalled an K&N FIPK kit it was torn in two spots. If this is torn I have an extra one that is used in good shape for sale.

 

i just adjust the idle level by ear and looking at the tach

 

idk, its weird but the idle problem just went away...weird huh. I still think the idle is set too high. I didn't end up looking at her at work but i'll try and adjust the idle by ear, i just wanted it precise thanx for the help guys...